I. Field of the Invention
The present invention relates to an improved method and the related system for pneumatically transporting powdered or granular materials stored in an air-tight storage container to a collector through a transport pipe in high density and at a slow speed by applying pressurized gas.
II. Prior Art
FIG. 10 shows a pneumatic transport system for use with powdered or granular materials which is of a general type conventionally used.
The system is constructed such that powdered or granular materials stored in an airtight storage container 100 are fed from the container 100 to a lower pipe 102a of a transport pipe 102 by the gas supplied from a gas feed pipe 101, and the materials are formed into a plug 105 (FIG. 11) by applying pressurized gas intermittently from a pressure nozzle 103 disposed in the half way of the lower pipe 102a, and then the plug is pneumatically transported in an upper pipe 102c of the transport pipe 102 through an inclined pipe 102b and are finally received by a collector 104.
However, when the powdered or granular materials are pneumatically transported in the form of a plug by the system described above, clearance is often generated above the plug while it passes through the transport pipe 102 as shown in FIG. 11, with the result that powdered or granular materials 106 on the surface of the plug 105 are first transferred and the plug would be early broken, thus eventually resulting in segregation.
Furthermore, since any of those conventional feeding systems delivers the plug at an extremely fast speed like several meters per second for example, the plug would be obliged to incur strong shock when being caught by collector 104, thus easily incurring chipping or breakage.
As a result, when such a conventional system is used for transporting medicine materials such as tablets requiring protection of finest quality from even the slightest crack, chipping, and breakage, the rate of producing inferior goods increases, and thus, actually, any of those conventional systems cannot have been used for transporting medicine materials up to now.
After following up research and tests time and again for completely solving those problems inherent in the conventional system mentioned above, the present invention resulted.
A method and the related system for pneumatically transporting powdered or granular materials in the form of a lengthy column in high density and at a slow speed was disclosed in Japanese Patent Application No. 61-251172(1986).
However, this prior invention needs insertion operation of a specified transport plug into the material transport pipe at a specific timing while pneumatically transporting powdered or granular materials in the transport pipe by applying pressurized gas. This in turn obliges the system related to the prior invention to constantly follow up troublesome timing control operations. In addition, when powdered or granular materials corresponding to the final batch are pneumatically transported in the transport pipe, pressurized gas charged both in the transport pipe and in the airtight storage container either would be forcibly discharged through the space generated above the materials in the transport pipe, thus causing part of the materials in the transport pipe to remain there, or would forcibly discharge the materials from the pipe due to "blow-out phenomenon", eventually incurring strong shock. Therefore, it leaves some room for improvement to the prior invention described above.
FIG. 12 illustrates variations of the internal pressure P and wind volume Q inside of the airtight storage container while the materials are pneumatically transported by means of pressurized gas.
It should be noted that since the pressurized gas charged in the airtight storage container is quickly discharged when the remaining materials corresponding to final batch pass through the material transport pipe, wind volume Q suddenly increases to easily cause the "blow out phenomenon".